Hydroxypropyl cyclodextrin is a propylene glycol ether of cyclodextrin. Cyclodextrins are produced from starch by enzymatic conversion. Hydroxypropyl cyclodextrin can either be plant-derived or synthetic. In cosmetics and personal care products, hydroxypropyl cyclodextrin functions as a chelating agent and stabilizer. The Personal Care Product Council’s online ingredient dictionary defines chelating agents as, “ingredients that complex with and inactivate metallic ions to prevent their adverse effects on the stability or appearance of cosmetic products.”

Metallic impurities in cosmetic products can come from many different sources. For instance, the ingredients themselves, especially those that are naturally derived, may have metallic impurities. Additionally, the water system or minute extractions from metallic equipment and storage containers may contain impurities. If not deactivated, these metallic ions can deteriorate cosmetic products by reducing clarity, compromising fragrance integrity, and causing rancidity. The use of chelating agents like hydroxypropyl cyclodextrin helps to prevent deterioration and protects the integrity of skin care products from undergoing unwanted consistency changes, pH changes, odor changes, or texture changes.